Multi-stage transmission for vehicle

ABSTRACT

A multi-stage transmission for a vehicle may include an input shaft, an output shaft, first to fourth planetary gear devices disposed between the input shaft and the output shaft to transmit rotary force, each of them having three rotary elements, and at least six shifting elements connected to the rotary elements of the planetary gear devices, wherein a first rotary element of the first planetary gear device is continuously connected to the input shaft and variably connected to a second rotary element of the first planetary gear device, the second rotary element is installed to be fixable by one shifting element of the at least six shifting elements, and a third rotary element of the first planetary gear device is continuously connected to a second rotary element of the second planetary gear device and variably connected to a third rotary element of the third planetary gear device.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No.10-2015-0080471, filed Jun. 8, 2015, the entire contents of which isincorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a multi-stage transmissionfor a vehicle and, more particularly, to a multi-stage transmissiontechnology able to realize as many shifting stages as possible using thefew parts and the simple configuration as far as possible, therebyimproving fuel efficiency of a vehicle.

2. Description of Related Art

Recent rising oil prices have driven worldwide car manufacturers intounlimited competition to improve fuel efficiency. In addition, greatefforts have been made to reduce the weight and improve the fuelefficiency of engines based on a variety of techniques such asdownsizing.

Meanwhile, among methods that can be sought for transmissions equippedin vehicles to improve fuel efficiency, there is a method allowing anengine to operate at more efficient operation points using themulti-staging of a transmission, thereby ultimately improving the fuelefficiency.

Further, such the multi-staging of a transmission allows an engine to beoperated in a relatively low revolution per minute (RPM) range, therebyfurther improving the quietness of a vehicle.

However, as the number of shifting stages of a transmission increases,the number of internal parts constituting the transmission alsoincreases. This may lead to undesirable effects instead, such as thereduced mountability and transfer efficiency and the increased cost andweight of the transmission. Therefore, in order to maximize the effectof the improved fuel efficiency using the multi-staging of atransmission, it is important to devise a transmission structure able torealize maximum efficiency using a small number of parts and arelatively simple configuration.

The information disclosed in this Background of the Invention section isonly for enhancement of understanding of the general background of theinvention and should not be taken as an acknowledgement or any form ofsuggestion that this information forms the prior art already known to aperson skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing amulti-stage transmission for a vehicle that is able to realize at leastten forward shifting stages and one reverse shifting stage with arelatively small number of parts and a simple configuration such that anengine may be operated at optimum operation points, thereby maximizingan improvement in the fuel efficiency of the vehicle, and the engine maybe operated more quietly, thereby improving the quietness of thevehicle.

, a multi-stage transmission for a vehicle according to the presentinvention may include: an input shaft; an output shaft; a first tofourth planetary gear devices disposed between the input shaft and theoutput shaft to transmit rotary force, each of the first to fourthplanetary gear devices having three rotary elements; and at least sixshifting elements connected to the rotary elements of the planetary geardevices. A first rotary element of the first planetary gear device maybe permanently connected to the input shaft and variably connected to asecond rotary element of the first planetary gear device, the secondrotary element of the first planetary gear device may be installed to befixable by one shifting element of the at least six shifting elements,and a third rotary element of the first planetary gear device may bepermanently connected to a second rotary element of the second planetarygear device and variably connected to a third rotary element of thethird planetary gear device. A first rotary element of the secondplanetary gear device may be permanently fixed, and a third rotaryelement of the second planetary gear device may be variably connected toa third rotary element of the fourth planetary gear device. A firstrotary element of the third planetary gear device may be permanentlyconnected to a first rotary element of the fourth planetary gear device,a second rotary element of the third planetary gear device may bepermanently connected to the input shaft, and the third rotary elementof the third planetary gear device may be variably connected to a secondrotary element and the third rotary element of the fourth planetary geardevice. The second rotary element of the fourth planetary gear devicemay be permanently connected to the output shaft.

The first planetary gear device, the second planetary gear device, thethird planetary gear device and the fourth planetary gear device may besequentially arranged along an axial direction of the input shaft andthe output shaft.

The second rotary element of the first planetary gear device may beinstalled to be fixable to a transmission case by means of a thirdclutch from among the at least six shifting elements, and the othershifting elements from among the at least six shifting elements may beconfigured to constitute variable connection structures between therotary elements of the planetary gear devices.

A first clutch from among the at least six shifting elements may form avariable connection structure between the first rotary element of thefirst planetary gear device and the second rotary element of the firstplanetary gear device; a second clutch from among the at least sixshifting elements may form a variable connection structure between thethird rotary element of the third planetary gear device and the secondrotary element of the fourth planetary gear device; a fourth clutch fromamong the at least six shifting elements may form a variable connectionstructure between the third rotary element of the first planetary geardevice and the third rotary element of the third planetary gear device;a fifth clutch from among the at least six shifting elements may form avariable connection structure between the third rotary element of thesecond planetary gear device and the third rotary element of the fourthplanetary gear device; and a sixth clutch from among the at least sixshifting elements may form a variable connection structure between thethird rotary element of the third planetary gear device and the thirdrotary element of the fourth planetary gear device.

Further, a multi-stage transmission for a vehicle according to thepresent invention may include: a first to fourth planetary gear deviceshaving three rotary elements, respectively; six shifting elementsconfigured to variably provide frictional force; and a first to eighthrotary shafts connected to the rotary elements of the first to fourthplanetary gear devices, wherein the first rotary shaft is an input shaftdirectly connected to a first rotary element of the first planetary geardevice and a second rotary element of the third planetary gear device,the second rotary shaft is directly connected to a second rotary elementof the first planetary gear device, the third rotary shaft is directlyconnected to a third rotary element of the first planetary gear deviceand a second rotary element of the second planetary gear device, thefourth rotary shaft is directly connected to a third rotary element ofthe second planetary gear device, the fifth rotary shaft is directlyconnected to a third rotary element of the third planetary gear device,the sixth rotary shaft is directly connected to a third rotary elementof the fourth planetary gear device, the seventh rotary shaft isdirectly connected to a first rotary element of the third planetary geardevice and a first rotary element of the fourth planetary gear device,and the eighth rotary shaft is an output shaft directly connected to asecond rotary element of the fourth planetary gear device; and whereinthe six shifting elements include a first to sixth clutches, the firstclutch is disposed between the first rotary shaft and the second rotaryshaft, the second clutch is disposed between the fifth rotary shaft andthe eighth rotary shaft, the third clutch is disposed between the secondrotary shaft and a transmission case, the fourth clutch is disposedbetween the third rotary shaft and the fifth rotary shaft, the fifthclutch is disposed between the fourth rotary shaft and the sixth rotaryshaft, and the sixth clutch is disposed between the fifth rotary shaftand the sixth rotary shaft.

The first planetary gear device, the second planetary gear device, thethird planetary gear device and the fourth planetary gear device may besequentially arranged along an axial direction of the input shaft andthe output shaft.

The first clutch from among the at least six shifting elements may forma variable connection structure between the first rotary element of thefirst planetary gear device and the second rotary element of the firstplanetary gear device; the second clutch from among the at least sixshifting elements may form a variable connection structure between thethird rotary element of the third planetary gear device and the secondrotary element of the fourth planetary gear device; the fourth clutchfrom among the at least six shifting elements may form a variableconnection structure between the third rotary element of the firstplanetary gear device and the third rotary element of the thirdplanetary gear device; the fifth clutch from among the at least sixshifting elements may form a variable connection structure between thethird rotary element of the second planetary gear device and the thirdrotary element of the fourth planetary gear device; and the sixth clutchfrom among the at least six shifting elements may form a variableconnection structure between the third rotary element of the thirdplanetary gear device and the third rotary element of the fourthplanetary gear device.

According to the present invention as set forth above, the multi-stagetransmission for a vehicle can realize at least ten forward shiftingstages and one reverse shifting stage with a relatively small number ofparts and a simple configuration such that the engine may be operated atoptimum operation points, thereby maximizing an improvement in the fuelefficiency of the vehicle, and the engine may be operated more quietly,thereby improving the quietness of the vehicle.

The methods and apparatuses of the present invention have other featuresand advantages which will be apparent from or are set forth in moredetail in the accompanying drawings, which are incorporated herein, andthe following Detailed Description, which together serve to explaincertain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating the configuration of a multi-stagetransmission for a vehicle according to an exemplary embodiment of thepresent invention.

FIG. 2 illustrates an operation mode table of the transmission shown inFIG. 1.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variousfeatures illustrative of the basic principles of the invention. Thespecific design features of the present invention as disclosed herein,including, for example, specific dimensions, orientations, locations,and shapes will be determined in part by the particular intendedapplication and use environment.

In the figures, reference numbers refer to the same or equivalent partsof the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of thepresent invention(s), examples of which are illustrated in theaccompanying drawings and described below. While the invention(s) willbe described in conjunction with exemplary embodiments, it will beunderstood that the present description is not intended to limit theinvention(s) to those exemplary embodiments. On the contrary, theinvention(s) is/are intended to cover not only the exemplaryembodiments, but also various alternatives, modifications, equivalentsand other embodiments, which may be included within the spirit and scopeof the invention as defined by the appended claims.

Referring to FIG. 1, a multi-stage transmission for a vehicle accordingto an exemplary embodiments of the present invention may include aninput shaft IN, an output shaft OUT, a first to fourth planetary geardevices PG1, PG2, PG3 and PG4 disposed between the input shaft IN andthe output shaft OUT to transmit rotary force, each of the first tofourth planetary gear devices PG1 to PG4 having three rotary elements,and at least six shifting elements connected to rotary elements of thefirst to fourth planetary gear devices PG1 to PG4.

A first rotary element S1 of the first planetary gear device PG1 may bepermanently connected to the input shaft IN and variably connected to asecond rotary element C1 of the first planetary gear device PG1. Thesecond rotary element C1 of the first planetary gear device PG1 may beinstalled to be fixable by one shifting element of the at least sixshifting elements. A third rotary element R1 of the first planetary geardevice PG1 may be permanently connected to a second rotary element C2 ofthe second planetary gear device PG2 and variably connected to a thirdrotary element R3 of the third planetary gear device PG3.

A first rotary element S2 of the second planetary gear device PG2 may bepermanently fixed to a transmission case CS, and a third rotary elementR2 of the second planetary gear device PG2 may be variably connected tothe third rotary element R4 of the fourth planetary gear device PG4.

A first rotary element S3 of the third planetary gear device PG3 may bepermanently connected to a first rotary element S4 of the fourthplanetary gear device PG4, a second rotary element C3 of the thirdplanetary gear device PG3 may be permanently connected to the inputshaft IN, the third rotary element R3 of the third planetary gear devicePG3 may be variably connected to a second rotary element C4 of thefourth planetary gear device PG4 and the third rotary element R4 of thefourth planetary gear device PG4, and the second rotary element C4 ofthe fourth planetary gear device PG4 may be permanently connected to theoutput shaft OUT.

In the present exemplary embodiment, the first planetary gear devicePG1, the second planetary gear device PG2, the third planetary geardevice PG3 and the fourth planetary gear device PG4 may be sequentiallyarranged along the axial direction of the input shaft IN and the outputshaft OUT.

The second rotary element C1 of the first planetary gear device PG1 maybe installed to be fixable to the transmission case CS by a third clutchCL3 from among the at least six shifting elements.

Therefore, the third clutch CL3 functions as brake such that the secondrotary element C1 of the first planetary gear device PG1 may beconverted to rotatable state or restrained state not to be rotated bythe operation of the third clutch CL3.

The other shifting elements from among the at least six shiftingelements may be configured to constitute variable connection structuresbetween the rotary elements of the planetary gear devices.

That is, a first clutch CL1 from among the at least six shiftingelements may form a variable connection structure between the firstrotary element 51 of the first planetary gear device PG1 and the secondrotary element C1 of the first planetary gear device PG1. A secondclutch CL2 from among the at least six shifting elements may form avariable connection structure between the third rotary element R3 of thethird planetary gear device PG3 and the second rotary element C4 of thefourth planetary gear device PG4. A fourth clutch CL4 from among the atleast six shifting elements may form a variable connection structurebetween the third rotary element R1 of the first planetary gear devicePG1 and the third rotary element R3 of the third planetary gear devicePG3. A fifth clutch CL5 from among the at least six shifting elementsmay form a variable connection structure between the third rotaryelement R2 of the second planetary gear device PG2 and the third rotaryelement R4 of the fourth planetary gear device PG4. A sixth clutch CL6from among the at least six shifting elements may form a variableconnection structure between the third rotary element R3 of the thirdplanetary gear device PG3 and the third rotary element R4 of the fourthplanetary gear device PG4.

In the present exemplary embodiment, the first rotary element S1, thesecond rotary element C1 and the third rotary element R1 of the firstplanetary gear device PG1 are a first sun gear, a first carrier and afirst ring gear, respectively. The first rotary element S2, the secondrotary element C2 and the third rotary element R2 of the secondplanetary gear device PG2 are a second sun gear, a second carrier and asecond ring gear, respectively. The first rotary element S3, the secondrotary element C3 and the third rotary element R3 of the third planetarygear device PG3 are a third sun gear, a third carrier and a third ringgear, respectively. The first rotary element S4, the second rotaryelement C4 and the third rotary element R4 of the fourth planetary geardevice PG4 are a fourth sun gear, a fourth carrier and a fourth ringgear, respectively.

The multi-stage transmission for a vehicle configured as above may alsobe presented as follows.

Specifically, the multi-stage transmission for a vehicle according to anexemplary embodiment of the present invention may include the first tofourth planetary gear devices PG1 to PG4 each having the three rotaryelements, the six shifting elements configured to variably providefrictional force, and eight rotary shafts connected to the rotaryelements of the first to fourth planetary gear devices PG1 to PG4.

Hence, from among the eight rotary shafts, the first rotary shaft RS1may be the input shaft IN directly connected to the first rotary elementSi of the first planetary gear device PG1 and the second rotary elementC3 of the third planetary gear device PG3. The second rotary shaft RS2may be directly connected to the second rotary element C1 of the firstplanetary gear device PG1. The third rotary shaft RS3 may be directlyconnected to the third rotary element R1 of the first planetary geardevice PG1 and the second rotary element C2 of the second planetary geardevice PG2. The fourth rotary shaft RS4 may be directly connected to thethird rotary element R2 of the second planetary gear device PG2. Thefifth rotary shaft RS5 may be directly connected to the third rotaryelement R3 of the third planetary gear device PG3. The sixth rotaryshaft RS6 may be directly connected to the third rotary element R4 ofthe fourth planetary gear device PG4. The seventh rotary shaft RS7 maybe directly connected to the first rotary element S3 of the thirdplanetary gear device PG3 and the first rotary element S4 of the fourthplanetary gear device PG4. The eighth rotary shaft RS8 may be the outputshaft OUT directly connected to the second rotary element C4 of thefourth planetary gear device PG4.

As set forth above, the multi-stage transmission for a vehicle accordingto an exemplary embodiment of the present invention including the foursimple planetary gear devices and the six shifting elements realizes tenforward shifting stages and one reverse shifting stage according to theoperation mode table as illustrated in FIG. 2. Since the multi-stageshifting stages of ten shifting stages can be embodied based on arelatively small number of parts and a simple configuration, themulti-stage transmission for a vehicle can contribute to the improvedfuel efficiency and quietness of a vehicle, thereby ultimately improvingthe marketability of the vehicle.

For convenience in explanation and accurate definition in the appendedclaims, the terms “upper”, “lower”, “inner” and “outer” are used todescribe features of the exemplary embodiments with reference to thepositions of such features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of thepresent invention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteachings. The exemplary embodiments were chosen and described in orderto explain certain principles of the invention and their practicalapplication, to thereby enable others skilled in the art to make andutilize various exemplary embodiments of the present invention, as wellas various alternatives and modifications thereof. It is intended thatthe scope of the invention be defined by the Claims appended hereto andtheir equivalents.

What is claimed is:
 1. A multi-stage transmission for a vehicle, comprising: an input shaft; an output shaft; a first to fourth planetary gear devices disposed between the input shaft and the output shaft to transmit rotary force, each of the first to fourth planetary gear devices having three rotary elements; and at least six shifting elements connected to the rotary elements of the planetary gear devices; wherein a first rotary element of the first planetary gear device is continuously connected to the input shaft and variably connected to a second rotary element of the first planetary gear device, the second rotary element of the first planetary gear device is installed to be fixable by one shifting element of the at least six shifting elements, and a third rotary element of the first planetary gear device is continuously connected to a second rotary element of the second planetary gear device and variably connected to a third rotary element of the third planetary gear device; wherein a first rotary element of the second planetary gear device is continuously fixed, and a third rotary element of the second planetary gear device is variably connected to a third rotary element of the fourth planetary gear device; wherein a first rotary element of the third planetary gear device is continuously connected to a first rotary element of the fourth planetary gear device, a second rotary element of the third planetary gear device is continuously connected to the input shaft, and the third rotary element of the third planetary gear device is variably connected to a second rotary element and the third rotary element of the fourth planetary gear device; and wherein the second rotary element of the fourth planetary gear device is continuously connected to the output shaft.
 2. The multi-stage transmission according to claim 1, wherein the first planetary gear device, the second planetary gear device, the third planetary gear device and the fourth planetary gear device are sequentially arranged along an axial direction of the input shaft and the output shaft.
 3. The multi-stage transmission according to claim 2, wherein the second rotary element of the first planetary gear device is installed to be fixable to a transmission case by a third clutch from among the at least six shifting elements; and the other shifting elements from among the at least six shifting elements are configured to constitute variable connection structures between the rotary elements of the planetary gear devices.
 4. The multi-stage transmission according to claim 3, wherein a first clutch from among the at least six shifting elements forms a variable connection structure between the first rotary element of the first planetary gear device and the second rotary element of the first planetary gear device; a second clutch from among the at least six shifting elements forms a variable connection structure between the third rotary element of the third planetary gear device and the second rotary element of the fourth planetary gear device; a fourth clutch from among the at least six shifting elements forms a variable connection structure between the third rotary element of the first planetary gear device and the third rotary element of the third planetary gear device; a fifth clutch from among the at least six shifting elements forms a variable connection structure between the third rotary element of the second planetary gear device and the third rotary element of the fourth planetary gear device; and a sixth clutch from among the at least six shifting elements forms a variable connection structure between the third rotary element of the third planetary gear device and the third rotary element of the fourth planetary gear.
 5. A multi-stage transmission for a vehicle, comprising: a first to fourth planetary gear devices having three rotary elements, respectively; six shifting elements configured to variably provide frictional force; and a first to eighth rotary shafts connected to the rotary elements of the first to fourth planetary gear devices; wherein the first rotary shaft is an input shaft directly connected to a first rotary element of the first planetary gear device and a second rotary element of the third planetary gear device, the second rotary shaft is directly connected to a second rotary element of the first planetary gear device, the third rotary shaft is directly connected to a third rotary element of the first planetary gear device and a second rotary element of the second planetary gear device, the fourth rotary shaft is directly connected to a third rotary element of the second planetary gear device, the fifth rotary shaft is directly connected to a third rotary element of the third planetary gear device, the sixth rotary shaft is directly connected to a third rotary element of the fourth planetary gear device, the seventh rotary shaft is directly connected to a first rotary element of the third planetary gear device and a first rotary element of the fourth planetary gear device, and the eighth rotary shaft is an output shaft directly connected to a second rotary element of the fourth planetary gear device; and wherein the six shifting elements include a first to sixth clutches, the first clutch is disposed between the first rotary shaft and the second rotary shaft, the second clutch is disposed between the fifth rotary shaft and the eighth rotary shaft, the third clutch is disposed between the second rotary shaft and a transmission case, the fourth clutch is disposed between the third rotary shaft and the fifth rotary shaft, the fifth clutch is disposed between the fourth rotary shaft and the sixth rotary shaft, and the sixth clutch is disposed between the fifth rotary shaft and the sixth rotary shaft.
 6. The multi-stage transmission according to claim 5, wherein the first planetary gear device, the second planetary gear device, the third planetary gear device and the fourth planetary gear device are sequentially arranged along an axial direction of the input shaft and the output shaft.
 7. The multi-stage transmission according to claim 5, wherein the first clutch from among the at least six shifting elements forms a variable connection structure between the first rotary element of the first planetary gear device and the second rotary element of the first planetary gear device; the second clutch from among the at least six shifting elements forms a variable connection structure between the third rotary element of the third planetary gear device and the second rotary element of the fourth planetary gear device; the fourth clutch from among the at least six shifting elements forms a variable connection structure between the third rotary element of the first planetary gear device and the third rotary element of the third planetary gear device; the fifth clutch from among the at least six shifting elements forms a variable connection structure between the third rotary element of the second planetary gear device and the third rotary element of the fourth planetary gear device; and the sixth clutch from among the at least six shifting elements forms a variable connection structure between the third rotary element of the third planetary gear device and the third rotary element of the fourth planetary gear device.
 8. The multi-stage transmission according to claim 5, wherein the first rotary element of the second planetary gear device is continuously fixed to the transmission case. 